This invention pertains to a portable tool for boring and refinishing seating surfaces in a ball valve, particularly and end-loading ball valve.
U.S. Pat. No. 4,114,483 provides a portable boring tool for refinishing the seal ring seating surfaces in a top-loading ball valve. In top-loading ball valves the ball depends by a lever mechanism into a valve body from a valve bonnet and is interposed between two oppositely-facing seating surfaces. The seating surfaces are both oriented approximately one degree from the perpendicular to a planar top surface of the valve. Unlike prior art devices, the tool disclosed in U.S. Pat. No. 4,114,483 facilitates the refinishing of top-loading ball valve seating surfaces in-line without removing the valves from the fluid lines they are controlling. The tool comprises a housing which contains gearing for ultimately transmitting motion from an input drive shaft to a cutter head assembly. The cutter head assembly is adapted to cut successively smaller circles of material from the surface being refinished.
Another type of ball valve, known as an end-loading ball valve, basically differs from the top-loading ball valve in that the lever mechanism enters the valve body laterally through a side opening rather than depending from the bonnet. In end-loading ball valves, selective communication occurs through two or more ports which communicate with a chamber in the valve body. The ball rotatably resides in the chamber and bears against a lower ball seal ring fitting in a lower seating surface which lies in a plane essentially parallel to the planar top surface of the valve body. An upper ball seal ring fits in an upper seating surface which resides in the valve bonnet. The lower and upper ball seal rings both bear tightly against the ball but allow the ball to rotate. Depending on the rotational position of the ball, passages through the ball selectively permit the flow of fluid therethrough from one port to another port. In this regard, the bonnet of some types of ball valves is often provided with a port and an elbow fitting.
Some end-loading ball valves additionally have a seal ring such as an O-ring which fits in a seating surface lying in a plane parallel to and near the valve body top surface to form a seal between the valve body and a portion of the bonnet which fits into the valve body. In other end-loading ball valve configurations, however, the bonnet fits on the valve body without the need for such a seal ring.
The seating surfaces for the seal rings in an end-loading ball valve can develop leaks and need to be refinished to remove corrosion, cuts, and porous regions. The tool provided in U.S. Pat. No. 4,114,483, however, is not adapted to refinish the seating surfaces in end-loading ball valves since such seating surfaces lie in planes parallel to the valve top surface. Hence, hitherto it has been customary to remove end-loading ball valves from the lines, transport them to a remote location where they are refinished, and then return them to their initial site. This procedure is both time-consuming and costly.